Software Vault: The Diamond Collection/The Diamond Collection (Software Vault)(Digital Impact).ISO/cdr47/sch250.zip/ERRORS.DOC

Text File | 1995-02-01 | 6KB | 118 lines

                    Error Detection During Execution

  As mentioned above, errors are trapped at run time and displayed in a
  red box on the screen. Error messages are standard Clipper(r) derived
  messages with  hooks to  the development  environment that  point the
  Schooner editor  back to the  line of code  that generated the error.
  This allows  Schooner to  load the file  that contains  the error and
  place the cursor on the line of code with the error.

  Error messages  generally describe  the error well.  However, not all
  messages are  easy to trace.  For the most  part, error messages will
  define the  function, the  internal (not Schooner)  line of offending
  code and a description of the error.

  The function described  in the error message  will most likely be the
  Schooner named function, but it may be an internal function. If it is
  an  internal  function,  don't panic.  The  error  is  probably  in a
  Schooner command  or variable declaration. Let  Schooner point you to
  the line of Schooner code and fix the error.

  Though  rare, some  errors may  generate  a condition  where Schooner
  cannot  point you  back  to the  line  of code.  These  are generally
  database file errors that  corrupt the file handles used by Schooner.
  This does not cause damage. It simply means you have to manually load
  the source code file and find the error yourself.

  Even more  rare are those errors  which dump you  back to DOS. Again,
  they rarely cause damage, but you will need to restart Schooner.

  Some errors  that can be  generated while in  graphics mode cannot be
  trapped by Schooner. This  most often occurs if your IMGSAVE() and/or
  IMGRESTORE() segment size definition is not evenly divisible into the
  number of  lines of  the image  with which  you are  working. See the
  IMGSAVE() and  IMGRESTORE() functions for more  details. The best way
  to  recover is  to try  blindly typing  the DOS  MODE 80  command and
  pressing ENTER, If  this does not work then  reset your PC. In all of
  our development we have never lost data. It is simply troublesome.

  Make liberal use of the  SETEXIT() function to allow you to break out
  of infinite  loop conditions.  In emergencies use  the Alt-C command.
  This will  kill almost  any situation and  return you  to DOS. Simply
  restart Schooner to fix the problem.

  The following are some of the more common errors:

  Database Required: You attempted to access a non existent database.

  Lock Required:  You tried  to perform  a function  which required the
  file or  record to be  locked. Use  the file exclusively  or lock the
  file or record.

  Exclusive Required: Similar to above. Use the file exclusively.

  Field Numeric Overflow:  You tried to write  a number into a database
  field  where the  size of  the number  is larger  than the  field can
  handle.

  Index File Corrupted: You have a damaged index file. Reindex.

  Type Mismatch: You tried to join or work on two variables that are of
  a different type.

  Subscript Range:  You tried  to use  an array  element that  does not
  exist.  In  rare  situations this  message  may  appear  if  you have
  unbalanced IF..ENDIF or DO WHILE..ENDDO constructs.

  Zero Divide: You tried to divide by 0.

  Run Error: Occurs when a SHELL() error condition arises.

  Open Errors: These can occur  when an error arises during a file open
  attempt. A number  is included with the  error that describes the DOS
  error type.  Refer to your DOS  manual for a  full description of the
  error type.

  Print Errors: Generally occur  when the printer is off-line or out of
  paper.

  Undefined Identifier:  You tried to  use a variable  that has not yet
  been defined.  Use the  PUBLIC command  to define  it or  assign it a
  value. This can also occur when an IF or DO WHILE statement  tries to
  evaluate  an expression  with an  undefined  variable (EVEN  WHEN THE
  STATEMENT IS NESTED WITHIN  A FALSE CONSTRUCT. This can occur because
  all IF and DO WHILE structures are evaluated in order to maintain the
  internal structure stacks).

  Not an Array: You tried to use an array element that does not exist.

  Missing External: Generally refers  to misspellings in your code that
  refer to commands or functions.

  Internal Error: An ugly one. Could mean a corrupted index file.

  Disk Full: Just like it sounds.

  Multiple Error:  Several errors  have occurred at  once. Another ugly
  one. You will probable get dumped back to DOS.

  Out of  Memory: You have run  out of memory.  Try modifying the above
  listed memory  management variables to  open up some  more memory. In
  particularly  large  applications, try  running  your  code  with the
  SCHOONRT runtime module rather than directly from the editor. This is
  a hassle, but opens up more memory.

                       Compiling your Application

  For  the most  part,  Schooner  Version 2.50  GUI  is  still compiler
  compatible with the Clipper Summer '87 compiler. However, maintaining
  compiler compatibility was  beginning to restrict our enhancements to
  Schooner and was actually holding back development.

  Because of this and due to low demand for the compiler kit, we are no
  longer offering the compiler  kit directly. However, we will be happy
  to work with you and advise you on the tools and techniques necessary
  to  compile your  Schooner  applications.  Please contact  us  at our
  mailing or CompuServe address listed in the README documentation.